||At the radio station in Humain, operated by the SIDC, a solar burst was detected. On May 05, 2009,
scientists from the SIDC noticed an enhanced solar radio signal. The burst lasted nearly 3 minutes and is seen as a bright
line in the diagram. The color in the diagram is related to the intensity of the signal. This is a so
called type II radio burst. It is a shock in this particular case produced by a coronal mass ejection, a CME.
The shock in front of the CME triggers the radio emission. The frequency of this emission is a measure for the
distance from the Sun: the higher the frequency, the closer to the Sun. When the frequency decreases with time,
the shock propagates away from the Sun. How fast the frequency decreases is a measure of the speed of the shock.